From MedScape:  Polyhydramnios is usually defined as an amniotic fluid index (AFI) of more than 24 cm or a single pocket of fluid at least 8 cm in depth that results in an amniotic fluid volume of more than 2000 mL.[4]
http://reference.medscape.com/article/975821-clinical 

 

Here's a great article about polyhydramnios (extra fluid). http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3964358/ It has the numbers so you can see how much over the limit you are. That might help you in making your decision.

Concerns are 
i) more space for baby to move about so greater chance of breech or sideways, or unstable lie (no set position which can mean in labour it goes breech or sideways).
ii) baby's cord coming before the baby's head and getting squashed.(cord prolapse - would need to be caesarean)
iii) baby does not engage, so pressure not on cervix, so longer labour, baby not move down.

This article from an excellent US midwife explains about how breaking the waters in a controlled way can ensure a baby is in a good position. She doesn't do home births with polyhydramnios, because legally she can't, but at the end of the article she gives an account of how she would manage it in a home birth situation. http://www.gentlebirth.org/archives/polyhydr.html
Here's a quote from the first paragraph: So, in many cases, a diagnosis of polyhydramnios means that you're on the high side of normal for amount of amniotic fluid and presents only minor secondary concerns.

Cochrane database (most highly rated scientific review site) had this article about Chinese medicine treatment to reduce fluid.
http://onlinelibrary.wiley.com/.../DARE.../frame.html
This is from the home birth reference site about what if there was a cord prolapse at a home birth:
http://www.homebirth.org.uk/whatif.htm#cord
Induction is usually offered for polyhydramnios.
Arguments for induction for polyhydramnios:
- get baby out before baby gets stuck in less favourable position
- complications of related condition e.g. GD

arguments against induction with polyhydramnios
- possible increased risk of cord prolapse, especially with breaking of waters. Usually it moves out of the way when baby moves down into the pelvis in late pregnancy. If your baby is engaged then there is less likelihood of cord prolapse.
- all the risks of induction 

You might like to have several plans in place, e.g.
Plan A, if baby is head down, stable lie (head down at every check in the last couple of weeks), and engaging go for home birth
Plan B, go for home birth and see where baby is on the day, if head down and low, stay at home, but if labour takes a long time or baby doesn't move down then go in.
Plan C, wait for labour to start spontaneously, and then go to hospital for waters to be broken in a controlled way.
Plan D, induction at 41 weeks
Or whatever you decide.